<!doctype html> 
<html> 
<head> 
    <meta charset="utf-8"> 
    <title></title> 
</head>
<body>

<script type="text/javascript">


var a = function(){

	setTimeout(()=>{
		this.c = 20;
	},10);
	//var _this = this;
	/*
	setTimeout(function(_this){
		_this.a = 10;
		//alert(this)
	},10,this)
*/
};
new a();
setTimeout(function(){
	alert(new a().c);
},100);
//alert(new a().a.n.k);
//alert(c);
//alert(new a());

</script>
</body>
</html>